Locking devices for doors

ABSTRACT

The locking device comprises a latch provided for a door or a casing, a first slidable member having a hook adapted to cooperate with the latch and provided for the casing or the door, spring means to bias the first slidable member in the longitudinal direction for engaging the hook with the latch, a second slidable member driven by the first slidable member, and a manually operated locking member for normally locking the second slidable member.

United States Patent m1 [1 11 3,918,750 Okamoto 1 Nov. 11, 1975 ILOCKING DEVICES FOR DOORS 105mm ill/Wot) Humphries to 70/70 x 3.5.3 3..7()b7X [75] lnventor: HaJlme ()kamoto. Kawasaki, Japan 7 h h l) m )7MIN) {73] Assignee: Yashiea C0., Ltd.. Tokyo. Japan Irimur1.;'.\'um1'm'/'Riehard Moore 22 Filed: Dan 6 19.73 Allurner, i-igvnl, 0rI'1rn1( l'lllflCS W. Helzer [2i Appl. No.: 422,314 [57] ABSTRACT ForeignApplication Priority Data The locking device C(IIHPIISSS 11 latchprovided for it door or a easing, u hrst sliduble member having ti12,1972 Japan --47|43605 hook adapted to cooperate with the latch andprovided for the casing or the door, spring means to bias [52] U.S. Cl292/106; 292/127 the first sliduble member in the longitudinal direction[51 1 Int. Cl.'- EQSC 1/06 for engaging the hook with the latch. 11second sliduble l l Field Of Search 70/69, 70, 71 72. 73. member drivenby the first sliduble member and at 70/74, 75, 76; 292/l06. 127, 150.174, DIG. manually operated locking member for HUITIlLlll) lock- 48 ingthe second slidnble member.

[56] References Cited 6 Claims. 5 Drawing Figures UNITED STATES PATENTSI 1546149 3/1951 BOWZCI' 292/150 X US. Patent N0v.11, 1975 Sheet10f33,918,750

US. Patent Nov. 11, 1975 S heet20f3 3,918,750

6 5.1) WWW US. Patent Nov.11, 1975 Sheet30f3 3,918,750

LOCKING DEVICES FOR DOORS BACKGROUND OF THE INVENTION This inventionrelates to a door locking device for locking the door of a casingadapted to house a photographic camera for example.

A locking device for locking a door to a casing generally comprises alatching member provided for either one of the door and the casing and aslidable member mounted on the other of said door and casing andincluding a hook engageable with said latching member. A locking devicehaving a construction described above, however, has a tendency ofaccidental opening of the door so that it is impossible to apply such alocking device for a door of a casing which is required to maintain itstemperature or pressure at a predetermined value or to maintainphotosensitive material contained in the casing in the dark.

For example, where such a door locking device is used for a rear lid ofa photographic camera, the outer end of the slidable member is bent upto project to the outside of the casing to be operable by the fingers ofthe user. Thus, the user of the camera operates such a projected endwith his fingers to open and close the rear lid of the camera. However,such a projected end may be readily engaged by clothes or casing of thecamera causing an accidental opening of the rear lid when the camera iscarried without housing it in the casing or when the camera is taken outof the casing. For this reason, in the prior art locking devices, forthe purpose of preventing such an accidental opening, the force of aspring adapted to hold the slidable member in the locked position hasbeen increased or a locking button for locking the movement of theslidable member has been provided so that unless the locking button hasbeen operated the slidable member can not be moved. With the former, itis impossible to operate the locking device with a small force whereaswith the latter construction as the locking button and the slidablemember immediately restore their original state, that is the lockedstate, it is necessary to manually operate the locking button so as tofree the slidable member in order to lock the door. I have proposed animproved construction that can obviate this disadvantage. According tothis improved construction the hook provided for the slidable member ismade to be resilient so that the hook is flexed to permit engagementwith the latch when the door is closed. However, such a hook becomesbrittle in a relatively short interval and requires strict control ofthe quality of material and high degree of accuracy of assembling.

SUMMARY OF THE INVENTION It is an object of this invention to provide animproved locking member for a door adapted to close an opening of acasing and with respect to which it is not necessary to operate alocking button for closing or opening the door.

Another object of this invention is to provide an improved door lockingdevice which can be readily fabricated without a high degree ofaccuracy, can prevent accidental opening of the door and has a rigid andcompact construction.

Still another object of this invention is to provide an improved doorlocking device wherein the relative movement of various parts of thelocking device is small thus decreasing damage and fault caused by wear.

In accordance with this invention, these and further objects can beaccomplished by providing a locking device for a door adapted to closean opening of a casing comprising a latch, a first slidable memberhaving a hook adapted to cooperate with the latch, the latch beingprovided for one of the door and the casing and the slidable memberbeing provided for the other, means to bias the first slidable member inthe longitudinal direction for engaging the hook with the latch, asecond slidable member driven by the first slidable member, and amanually operated locking member for normally locking the secondslidable member.

BRIEF DESCRIPTION OF THE DRAWINGS The invention can be better understoodfrom the following detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is an exploded perspective view of a locking device embodying theinvention and applied to a rear lid of a photographic camera;

FIG. 2 is a plan view of an assembled locking device;

FIG. 3 shows a section taken along a line III-11] in FIG. 2

FIG. 4 is a view similar to FIG. 3 with the locking device shown in theunlocked position and FIG. 5 is an exploded perspective view of amodified embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The door locking device of thisinvention shown in FIGS. 1 to 4 of the accompanying drawings is used tolock the rear lid or door 2 which is hinged to the body or casing 1 of aphotographic camera. The free end of the lid 2 is bent up and a plate 4having a latch 3 at the center is secured to the outside of the bent upportion. A pair of pins 5 and 6 are secured to one side of the camerabody 1 to which the plate 4 is secured to support a cover plate 7 whichis secured to the pins 5 and 6 by means of screws 8 and 9 as shown inFIG. 3. Slidable members 12 and 13 having slots 10, 11, 10' and 11adapted to receive pins 5 and 6 are disposed in a space between thecover plate 7 and the camera body 1. The slidable members 12 and 13 aresuperposed each other and are slidable in the longitudinal direction.

One end of upper slidable member 12 extends beyond the corresponding endof the cover plate 7 and is formed with a flange 14. A key hole 15having a diameter of D and a slot 16 having a width d and contiguous tokey hole 15 are formed through slidable member 12 and a pin 17 issecured to the lower surface of the slidable member 12 at about themiddle of the length thereof. The lower slidable member 13 is providedwith a letter L shaped lateral hook 18 in the same plane as the slidablemember 13. The outer end of the hook 18 is slanted as at 18a. On theopposite sides of the key hole 15 and slot 16, the lower slidable member13 is provided with an elliptical slot 19 having a width D which issubstantially equal to or slightly larger than the diameter D of keyopening 15 and a slot 20 adapted to receive pin 17. A recess 22 isformed on one surface of the camera body 1 to receive a compressionspring 21 having one end engaged with the lower slidable member 13 tourge it in the locking direction. A recess 23 is provided for the camerabody 1 beneath key hole 15 and elliptical slot 19 to receive a lockingbutton 25 which is normally urged to project upwardly by a compressedspring 24. The head 26 of the locking button 25 is normally projectingto the outside of an opening 27 through the cover plate 7. The lockingbutton 25 is provided with an annular locking member 28 having an outerdiameter corresponding to the diameter D of key opening I5, a reduceddiameter portion 29 on the upper side of the locking member 28 andhaving a diameter corresponding to the width d of slot 16, and a lowerflange 30 having a diameter larger than the width of the elliptical slot19.

When the rear lid 2 is closed, various parts of the locking deviceassume the positions shown in FIGS. 2 and 3. More particularly, thelatch 3 of the stationary plate 4 is positioned in a gap defined betweenthe hook 18 and the lower slidable member 13 thereby locking the same.Under these circumstances, the locking member 28 of the locking button25 is in a locking engagement with the key hole 15 of the upper slidablemember 12 but the lower slidable member 13 is not locked because thewidth D of the elliptical slot 19 is larger than the diameter of thelocking member 28. To release the locking engagement of the lockingmember 28 with the key hole 15, the locking button 25 is depressed by afinger as shown in FIG. 4 to bring the reduced diameter portion 29 intoalignment with the slot 16. At the same time, the flange I4 is pulled tomove the upper slidable member 12 in the direction of arrow C shown inFIG. 4. Since pin 17 is engaging slot 20 the lower slidable member 13 isalso moved together with the upper slidable member 12, thus disengaginghook 18 from latch 3. When the slidable member 12 is re leased it willbe returned from the position shown in FIG. 4 to the position shown inFIGS. 2 and 3 by being pulled by the lower slidable member 13 and theaction of return spring 21. As the slidable members 12 and 13 reset, thelocking button is projected upwardly to again lock the slidable member12.

In order to close the rear lid 2 for the purpose of locking again latch3 and hook 18, the lid 2 is pressed in the direction of arrow B shown inFIG. 1. When the latch 3 is urged against the inclined surface 180, thelower slidable member 13 is urged in the direction of A. As soon as thelatch 3 enters into the gap between the hook 18 and the slidable member13, the slidable member 13 is reset by the action of the compressionspring 21 thus locking latch 3 with hook 18.

According to a modified embodiment shown in FIG. 5, two slidable members51 and 52 are arranged in the same plane which correspond to slidablemembers 12 and 13, respectively of the previous embodiment. Although theslidable members 51 and 52 have the same function as the slidablemembers 12 and 13, pin 17 is replaced by a hook 55 provided for theslidable member 51. To further stabilize the operation of the slidablemembers 51 and 52, a guide wall 56 is provided for the camera body 1 toassist pins 53 and 54. This modified embodiment is suitable wheresufficient height is not available to install the locking device.

With the locking device of this invention, even when weak springs areused for biasing the slidable members and the locking button it ispossible to prevent any accidental opening of the rear lid or door andthe door can be opened and closed with a small force. Finally, it shouldbe noted that two separate manual operations are required to release thelocking device, and hence, open the lid or door, as opposed to a singlemanual operation to effect closing. Hence, the possibility of accidentalopening of the lid or door is minimized.

According to this invention it is only necessary to manufacture variousparts at high accuracies but it is not necessary to adjust them at thetime of assembly.

For this reason, it is possible to decrease the number of process stepsfor assembly and the cost of manufacturing. Moreover, since the relativemovements between various parts are small and since the parts are heldstable in respective positions, damage of the parts: due to. wear issmall thus decreasing the chance of fault and misoperation.

What is claimed is:

l. A locking device for a door adapted to close an opening of a casingcomprising a latch, a linearly slidi able member having a hook slidablealong a linear path to engage in interlocking relationship withsaidilatch',

said latch being provided for one of said door and cas- 7 ing and saidslidable member being provided for the other, biasing spring means tobias said slidable member longitudinally along a linear path in adirection for engaging said hook with said latch, manually operatedmeans engaging said slidable member for longitudinally sliding saidslidable member along the linear path in a direction opposite to that ofthe biasing spring means for releasing the latch, a manually operatedlocking member engageable with said slidable member for locking theslidable member against movement, and second biasing spring means fornormally biasing said locking member into locking engagement with saidslidable member.

2. The locking device according to claim I wherein said slidable membercomprises first and second slid I able members provided with alignedguide slots adapted to accommodate guide pins secured to said casing,and said first and second slidable members are.-

superposed upon each other and secured together.

3. The locking device according to claiml wherein said slidable memberis formed with a key hole and a slot contiguous to and extending intosaid key hole with said slot having a width smaller than said key holeand said locking member comprises a locking button received in said keyhole said locking button having a lower larger diameter portioncorresponding to the idiameter of said key hole and an upper reduceddiameter. portion having a diameter corresponding to the width of saidslot, and said second biasing spring means comprises a biasing springfor normally urging said locking button upwardly for fitting said lowerlarger diameter portion in said key hole for securing said lockingdevice in a closed position.

4. The locking device according to claim 3 wherein 1 i connected byadditional hook means.

1. A locking device for a door adapted to close an opening of a casingcomprising a latch, a linearly slidable member having a hook slidablealong a linear path to engage in interlocking relationship with saidlatch, said latch being provided for one of said door and casing andsaid slidable member being provided fOr the other, biasing spring meansto bias said slidable member longitudinally along a linear path in adirection for engaging said hook with said latch, manually operatedmeans engaging said slidable member for longitudinally sliding saidslidable member along the linear path in a direction opposite to that ofthe biasing spring means for releasing the latch, a manually operatedlocking member engagable with said slidable member for locking theslidable member against movement, and second biasing spring means fornormally biasing said locking member into locking engagement with saidslidable member.
 2. The locking device according to claim 1 wherein saidslidable member comprises first and second slidable members providedwith aligned guide slots adapted to accommodate guide pins secured tosaid casing, and said first and second slidable members are superposedupon each other and secured together.
 3. The locking device according toclaim 1 wherein said slidable member is formed with a key hole and aslot contiguous to and extending into said key hole with said slothaving a width smaller than said key hole and said locking membercomprises a locking button received in said key hole said locking buttonhaving a lower larger diameter portion corresponding to the diameter ofsaid key hole and an upper reduced diameter portion having a diametercorresponding to the width of said slot, and said second biasing springmeans comprises a biasing spring for normally urging said locking buttonupwardly for fitting said lower larger diameter portion in said key holefor securing said locking device in a closed position.
 4. The lockingdevice according to claim 3 wherein said slidable member comprises firstand second slidable members provided with aligned guide slots adapted toaccommodate guide pins secured to said casing, and said first and secondslidable members are superposed upon each other and secured together. 5.The locking device according to claim 1 wherein said slidable membercomprises first and second slidable members arranged on the same planeand interconnected by additional hook means.
 6. The locking deviceaccording to claim 3 wherein said slidable member comprises first andsecond slidable members arranged on the same plane and interconnected byadditional hook means.